1. Field of the Invention
This invention lies in the field of rotary drilling systems. More particulary, it is concerned with a type of automatic drilling system in which the traveling block and hook are supported and guided for motion along the axis of the rotary table by means of two guide cables, in tension, supported from the tower. Such a system is described in my copending application Ser. No. 241,508.
2. Description of the Prior Art
In the prior art it is customary to support the traveling block directly from the crown block, so that it nominally hangs on the axis of the rotary table. However, it is possible by applying lateral forces to the hook, or to a stand of pipe hanging from the hook, to move the hook in a direction lateral to the vertical travel axis.
In the system utilizing two elevators and using automatic means for disconnecting the hook from the elevators, etc., it is necessary to guide the vertical motion of the hook by means of guide cables. This prevents any lateral movement of the hook from the axis of the rotary table.
At the fourbleboard, which stands some 90 feet above the floor of the drilling platform, there is a pipe rack with a number of parallel fingers spaced apart a sufficient distance so that pipe, while standing on the floor, can be guided into one of these slots where it will be securely held. Because of the limited horizontal space that high in the tower, the fourbleboard is generally in the plane of the hook. Therefore, in removing a stand of pipe from the elevator to push it into one or another of the spaces or slots between the fingers, the hook must be turned a small angle of the order of 30.degree., so that the pipe will move directly into space between the fourbleboard and the fingerboard, or pipe rack. This is generally done manually by the tower man, standing on the fourbleboard, and is a very dangerous occupation. By the use of this improvement it now becomes possible to substantially automatically direct the pipe into the fingerboard with less physical danger to the tower man.